Hänvisningar finns i följande patent|
| US4046548 | 28 apr 1976 | 6 sep 1977 | Potters Industries, Inc. | Apparatus for producing spherical particles | | US4318691 | 10 okt 1980 | 9 mar 1982 | | Furnace for expanding mineral ores | | US5160710 | 8 nov 1991 | 3 nov 1992 | | Apparatus for continuous production of intumesced particles |
|
